Propeller control means



April 1953 N. R. RICHMOND ETAL 2,635,699

PROPELLER CONTROL MEANS Original Filed Dec. 9, 1941 5 Sheets-Sheet 1mvemoiz NELSON R- Ramon W.?ER\N,' BY MAURICE J. LEVY p A0 mania-r012 N g"4 W M ATTORNEY Ag 1953 -N. R. RICHMOND ETAL 2,635,699

PROPELLER CONTROL MEANS Qpigiinal Filed Dec. 9, 1941 5 Sheets-Sheet 2INVENTOR NELsoN Rilzmouo Am? PONALD W-PERIN,DECEASED,

BY MAmzlcs J- Law, ADMINISTRATOR ATTORNEY April 21,1953 N. R. RICHMOND'ETAL 9 'PROPELLER CONTROL MEANS Original Filed Dec. 9, 1941 5SheetsSheet 3 Jfivew Z171.- NELSON R. RICHMOND AND 1 0mm W- PeempiceAmBY MauRnce JUL'EVY, AOMINlSTRATOR April 21, 1953 N. R. RICHMOND ET AL2,635,699

PROPELLER CONTROL MEANS Original Filed Dec. 9, 1941 v v 5 Sheets-Sheet 4I m2 v 43 a z I I I7\6 62 .54 1 I 6 58 1m 1 P 48 /00- I 5; 60 /28 I I 144 I 7) 66 I A,

II \I I r9 I /58 l l P I Eis- INVENTOR NELSON K Rlcugoun Ann DONALD W-PERM; DECEASED,

Y MAumcE J. LEVY, Aommnsrkmoa @WQM ATTORNEY Patented Apr. 21, 1953PROPELLER CONTROL MEANS Nelson R. Richmond, Thompsonville, Conn., andDonald W. Perin, deceased, late of Greenfield, Mass, by Maurice J. Levy,administrator, Greenfield, Mass., assignors to United AircraftCorporation, East Hartford, Conn., a corpora tion of DelawareContinuation of application Serial No. 664,640,

April 24, 1946, which is a continuation of application Serial .No.422,252, December 9, 1941. This application February 21,- 1949, SerialNo.

An object of the invention resides in the provisionof a more accurateand sensitive control means for a propeller and one which is not subject1 to overshooting or hunting When acting under constant-speed operation.

A further object resides in the provision of an improved control meanswhich may be subjected to either manual or automatic operation at thewill of the operator. I M A still further object resides in theprovision of a propeller control means which does not require ahydraulic connection between the speed responsive governor and the pitchchanging mechanism of the propeller.

An additional object resides in the provision of an improved controlmeans having alternative governor controlled hydraulic means andmanually controllable electric means -for changing the pitch of thepropeller.

Other objects and advantages will be more particularly pointed outhereinafter or will become apparent as the description proceeds.

In the drawings,

Fig. 1 is a diagrammatic view of the improved propeller pitch controlmeans;

Fig. 2 is a transverse sectional view at the front end of the propellerdriving engine taken along the lines 2-2 of Fig. 2A with the controlhousing shown in full and showing the arrangement of the major elementsof the control apparatus around the front portion or nose pieceoi theengine. v

Fig. 2A is a longitudinal sectional view of the assembled propeller,engine and control section.

Fig. 3 is a longitudinal sectional view on an enlarged scale of a speedresponsive governor constituting one of the elements of the improvedcontrol apparatus.

Fig. 4 is a longitudinal sectional view of one element of an Autosyn orposition indicating device constituting another element of the improvedcontrol apparatus.

Fig. 5 is a longitudinal sectional view of another 27 Claims. (Cl.170-1602) elementof the Autosyn or position indicating device.

Fig. 6 is a front elevational view of the portion of the Autosyn shownin Fig. 5, and

Fig. 7 is a cross-sectional view on the line ll of Fig. 5 looking in thedirection of the arrows.

.Referring to the drawings in detail and particularly to Fig. l, thenumeral It] generally indicates a hydro-controllable feathering-typepropeller having a hub I I and the numeral l'2 generally indicates thepropeller driving engine from whichprojects the propeller drive shaft,generally indicated at l4. The propeller I0 is provided with suitablepitch changing apparatus such as hydraulic motors and, for the purposeof illustration, is shown as having an individual vane type for eachblade, one of such motors bein shown in section in Fig. land generallyindicated at [6. This motor has an outer relatively movable portion I8provided with a pair of diametrically opposed vanes 20 and 22 andconnected to the corresponding propeller blade and an inner relativelyfixed member 24 provided with a pair of diametrically opposed "vanes 26and 28. H3-

draulic fluid is supplied to the pitch changing motor or motors from asuitable source of hydraulic'fiuid under pressure, such as the pumpgenerally indicated at 30, through the pressure conduit 32 leading tothe distributing valve, generally indicated at'34, and from thedistributing valve alternatively tothe conduits 36 and 38 depending uponthe setting of the distributing valve as positioned to determine thedirection of propeller pitch change. When hydraulic fluid under pressureis supplied through one of the lines 36 or 38 to one side of the pitchchanging motors, fluid will drain from the opposite side of the pitchchanging motors, through the other line to the distributing valve 34"from which it will be conducted through the channel 48 to the sump orreservoir 42 connected with the intake side of the pump 30. -The pumpand sump are in the propeller hub, and the pump plungers 3| arereciprocated by stationary cam 33 during rotation of the propeller.

The distributing valve 34 is carried by the propeller l0 and iscontrolled by a speed responsive governor, generally indicated at 43 andparticularly illustratedin Fig. 3, driven from the engine by suitablemeans such as the gears 44, 46, 41 and 49. The governor 43 includes aset of centrifugally actuatedflyballs 48 which act against a slide valve50 in opposition to a speeder spring 52. The slide valve rotates andreciprocates in a fixed valve cylinder 54 and is provided with ports 56and 5B registerable with ports 69 and 62 in the fixed valve cylinder 54.A fluid pump 64, which may be driven by the governor drive gears 44, 46,41 and 49 from the engine I2, receives hydraulic fluid from thereservoir 66 through the conduits 68, I9 and I2 and supplies this fluidunder pressure through the conduits 14 and I6 and the pressure reliefvalve I9 to the valve cylinder port 62. From the valve cylinder port 69a fluid pressure line 89 leads through the solenoid controlled valves 82and 84 to the servo-motor, generally indicated at 86, which servo-motoroperates a shaft 98 connected through the displacement mechanism 99 androtational slip joint 92 with the plunger 94 of the pitch controllingdistributing valve 34 so that the distributing valve will be positionedto change the pitch of the propeller in response to governor demands forincrease or decrease in the speed of the power plant including theengine I2 and propeller I9. As shown in Figs. 2 and 2A, the displacementmechanism schematically shown at 99 in Fig. 1 comprises rack teeth 9Icut into shaft 88 and meshing with teeth 93 cut in a small portion ofthe circumference of sleeve 95 forming a portion of slip joint 92.Sleeve 95 is supported inside of an oil guard 91 which is secured to thecontrol support 99 by any suitable means. Oil guard 91 has spiral teethI9I cut in a portion of its inner circumference and sleeve 95 has matingspiral teeth I93 cut in a portion of its external circumference so thatlongitudinal movement of shaft 88 will cause rotation of sleeve 95 andthe spiral teeth I9I, I93 will cause longitudinal reciprocation of thesleeve and hence of the slip joint 92. Control support 99 is secured tothe nose of the engine by means of cap screws Within the slide valve 59there is a reciprocable pilot valve 96 projecting out of the open upperend of the slide valve and there pivotally connected to one end of alever member 98 which is pivotally connected at its opposite end to theupper end of a compensating plunger I99 and supported intermediate itslength on a fixed pivot I92. At its lower end the pilot valve 96 carriesa piston I94 adapted to close ofi the port 56v when the pilot valve isin its neutral position. When the piston I94 of the pilot valve 96 isabove the port 56 the fluid line 89 leading to the servomotor will beconnected with drain through the lower open end of the slide valve 59and when this piston I94 is below the port 56 the pressure line I6 willbe connected with the fluid line 89 to supply hydraulic fluid underpressure to the servo-motor.

The servo-motor 86 is arranged with two cylinders I96 and I98 in tandemand in each of these cylinders there is a reciprocable piston, asindicated at H9 and H2, respectively, both pistons being rigidly securedto the shaft 88. In the arrangement illustrated, the pressure line 89leads to the valve 62 and a branched conduit II4 connects the outlet ofthis valve with the inlet of the valve 64 and the outlet of which isconnected by a conduit II6 with the left hand end of the cylinder I98 sothat fluid under pressure supplied to the line 89 and the valves 62 and84 and conduits H4 and H6 will force the piston II2 to the right asviewed in Fig. l. The shaft 89 extends into a cylindrical casing IIS andcarries an abutment I29 within this casing which abutment bears againstone end of a compression spring I22 the opposite end of which bearsagainst the closed end of the casing. The spring I22 thus opposes theaction of the fluid under pressure on the piston H2 and urges the shaft.88 towards the left as viewed in Fig. 1.

The right hand end of both cylinders I96 and I98 are connected by anexhaust duct I24 with the sump 66 so that any fluid trapped in theseends of the tandem cylinders can be vented to the sump and will notinterfere with the operation of the pistons H9 and H2. The left hand endof the cylinder I96 is connected by the fluid line I26 with the bottomof the cylinder I28 within which the compensating plunger I99reciprocates. With this arrangement the piston I94 of the pilot valve ismoved to close the port 56 as the servomotor shaft 86, which adjusts thevalve 34, approaches a position corresponding to a governor speed changedemand and thus gradually retards the rate of movement of theservo-motor as the propeller pitch approaches an angle corresponding tothe speed change demand of the governor. It should be noted that thehydraulic system for the governor and its servo-motor and the separatehydraulic system for the propeller are both separate from andindependent of any lubricating system that may be used in the engine. Itis thus possible to use a fluid best suited to the governor or thepropeller without the limitation that that fluid shall also be suitablefor lubricating an engine.

The distributing valve 34 has an outer cylindrical casing I39 providedwith ports I32, I34, I36, I38 and I49 within which is a reciprocablesleeve member I42 operatively connected atone end with the propellerpitch changing mechanism by a suitable mechanical connectionschematically shown in Fig. 1 as a bell crank lever I 44 and a cam I46,the bell crank lever being maintained in contact with the cam by asuitable compression spring I46. In Fig. 2A the ports I32 and I49 ofFig. 1 are represented by the open right hand end of the sleeve I42 anda hole through the interior of plunger 94 and a hole I33 through theside of the plunger. The connection between the sleeve member I42 andthe propeller pitch changing mechanism is represented by gears I43, Iand I47, rotatable spiral cam I49, stationary member I5I, slotted at I53and by pin I55 passing through sleeve I42, slot I53 and cam slots I51 ofspiral cam I49. For a more complete description, reference may be madeto application Ser. No. 686,298, now Patent No. 2,462,932, filed by JohnE. Anderson for Pitch Changing Mechanisms. The valve plunger 94 projectsinto the sleeve I42 and is provided therein with spaced valve pistonsI59 and I52. The valve ports I 32 and I49 are connected through thedrain channel 49 with the sump 42 at the inlet side of the pump 39. InFig. 2A, the interior of hub II, Which receives oil discharged from theopen end of sleeve I 42, is connected with the sump 42 through a hollowscrew similar to screw I59 connecting conduit 32 with port I36. The portI34 is connected by the fluid channel 39 with one side of the hydraulicmotor I6. The port I 38 is connected by the fluid channel 36 with theopposite side of the hydraulic motor and the port I36 located at themid-length position of the distributor valve is: connected by the fluidpressure line 32 with the outlet of the pump 39 so that fluid underpressure is applied at all times to this intermediately positioned port.The valve sleeve I42 is provided with ports which are registerablyrespectively with the ports in the outer fixed casing I 39 over apredetermined range of relative movements between the sleeve and thecasing.

The operation of this distributing valve is such that when the plunger94 is moved in response to a governor demand for a speed change, oneside of the hydraulic motor will be connected with the. fluid underpressure while the other side will be connected with the sump and themotor will act to change the propeller pitch. However, as the propellerpitch is changed the sleeve I42 will be moved to close off theconnections between the'distributing valve and the propeller pitchchanging motor at a rate such that when the propeller pitch has beenchanged .a number of degrees sufiicient to correct the governorindicated deviation from the speed for which .the governor is set, thepitch changing motor will be stopped and locked against any furtherpitch change until the governor again changes the position of theplunger 84. Thus, the position of the plunger 94 is at all timesindicative of the pitch angle of the propeller blades.

The cylinder I28 is provided with a bleed vent I54 controlled by aneedle valve I56 the purpose of which is to permit the pilot valve toreturn to its neutral or centered position blocking the port 56 in thenormal position of the valve 50 under the influence of the centeringspring I58 as the governor 43 returns to its usual or on-speed positionwith the propeller pitch at the angle required to maintain the powerplant at the speed for which the governor is set, the on-speed positionof the governor being that in which the flyweights 48 are substantiallyparallel tothe axis of the governor drive shaft I60.

The speed setting of the governor may be varied by suitable means suchas the movable u abutment I62 disposed at the upper end of the speederspring 52 and moved by the rotatable pinion I64 the teeth of which meshwith suitable rack teeth provided in one side of the abutment, movementof the abutment by rotation of the pinion changing the loading on thespeeder spring in a manner to change the speed setting of the governor.The pinion may be rotated by manual or automatic means such, forexample, as the cable pulley I66 which may be connected by suitablecables with a manual control device, not illustrated.

The above-described mechanism will provide an automatic constant-speedcontrol of the power plant over a predetermined range of propeller pitchangles, the range of pitch angles being determined by suitable meanssuch as the limit stop I68 and I10 mounted on shaft 88 and cooperatingwith an electro-magnetically controlled plunger I12 which may beretracted out of contact with the limit stops for feathering or reverseoperations of the propeller as will be presently described.

The control has four different modes of operation as indicated on thedial I14 of the selector I16. These are, reading clockwise of the dialreverse, constant speed, manual control and feathering.

In Fig. 1 the selector is illustrated as set for constant-speedoperation as described above. With the selector knob I16 in the constantspeed position, the switch arms I18, I80 and I82 are all on dead contactpoints so that the solenoids of all of the solenoid valves 82, 84 andI84 and the solenoid I1I controlling the plunger I12 are de-energizedpermitting the respective projecting springs to move the various valvesand the limit stop plunger to the positions illustrated. One unit I86 ofan Autosyn system is operatively connected with the shaft 88 by suitablemeans such as the rack teeth I88 on the shaft and "a pinion I90 on theunit drive shaft I92. This unit I86 is connected by suitable electricalconduits I94 with a second Autosyn unit I96 the shaft I98 of which isconnected with indicating hands 200, 202 and 204 traveling over a fixeddial 206 bearing pitch angle degree indicia on the face thereof. One ofthe hands, for example, the hand 200 may be connected with the shaft I98in a manner to indicate the propeller pitch angle in degrees. Anotherhand, for example, the hand 202 may be connected with the shaft I98through a gear train in a manner to indicate the seconds component ofthe pitch angle of the propeller in much the same manner that the handsof a clock indicate hours and minutes on the clock dial. The third hand204 is connected to a gear 208 rotatable relative to the shaft I88 andis for use in manual control of the propeller pitch as will presentlyappear. Since theposition of the shaft 88 is always exactly correlatedwith the pitch angle of the propeller blades, it is apparent thatmovements of this shaft transferred through the Autosyn units I86 andI96 to the hands 280 and 202 Will at all times indicate the exact pitchangle of the propeller blades. Whenit is desired to place the propellerpitch changing mechanism under manual control, the control knob I16 isturned in a clockwise direction to the manual control setting and theselector knob 262 is turned until the indicating hand 204 is brought.to'the indicated pitch anglev at which it is desired to have thepropeller operate incidentally bringing the disc members 238 and 246 toa corresponding angular position by the operation of the respective discrotating gears, 268 and 210 mounted on the shaft 264 which car-. riesthe knob 262. The control mechanism will now function to main thepropeller pitch at the angle thus manually selected and the pitchianglemay be changed at any time by rotating the knob 262 to bring the pointer204 to a different position.

When the. selector knob I16 is moved to the manual control position thecontrol circuits are rearranged as follows. An energizing circuit forthe solenoid of the valve 82.is established through the conduit 224leading from they side 228 of the direct current source, the brush 226,the shaft 222, the contact arm I80, thecontact point 2I6, and theelectric conduit 2I8 leading to the valve, and from the valve throughthe conduit 230 to the opposite side 232 of the current source. Thisconduit will maintain the solenoid of the valve 82 energized at alltimes while the propeller is operating under manual control therebymoving the valve to block off the pressure line leading from thegovernor outlet, thus disconnecting the governor from the pitch controlmechanism, opening the line 258, which is closed during governor controlof the pitch changing mechanism. An energizing circuit for the solenoidof the valve I84 is established through the conduit 224, the brush 226,the shaft 222, the arm I18, the contact point 2I0, the conduit 2I2, thebrush 2I4, the shaft I88, the arm 254, the contact member 240 on thedisc 238, the brush 236 and the conduit 234 to one side of the solenoid,the connection from the opposite side of the solenoid being through theconduit 230 to the side 232 of thedirect current source as in the caseof the solenoid of the valve 82. The above-described circuit forenergizing the solenoid of thevalve I84 is complete only when the arm254 is on the semi-annular contact member"241l' and is broken when thearm 254 is in contact: with. the nonrconducting material. of theremainder of the disc 288'. The; making and breaking of this circuit iseffected by the: Autosyn. comprising the units. I86.- and; I98, whichrotates the shaft I98 as. the propeller; changes pitch. and. thus moves.the arm 254 relative to the disc. 238. When the. circuit is complete thesolenoid of the valve I84 is energized: moving thev valve. to interceptthe: fluid. conduit 322 and open the conduit 258. When the conduit 322-is intercepted fluid under pressure from' the outlet of the pressureregulatingvalve T8: is cut off and the left hand. end of the servo-motorcylinder I 08 is connected through the conduit. II.6,. the

valve 841, the conduit I1I4, the conduit 2.58, the servo-motor cylinderI06 and the conduit I24 with thesump 86. thus permitting the spring; I22to move the servo-motor to change the propeller pitch in one direction.When the circuit. is. broken the valve IN is in the condition.illustrated in. which the conduit 258. is intercepted cutting theservo-motor off from the drain and the conduit 322, is. opened.connecting the. servo-motor cylinder. I08 with the outlet of the;pressure relief valve I8 through the fluid channels 256, 322, I I4, and.H8 and the valve 84 thus admitting-fluid under pressure to theservo-motor to change the propeller pitch in the direction opposite tothat incident to movement of. the servo-motor by the spring I22. Thisoperation of. the valve I84: willcausethe propeller pitch to changeuntil. the pitch angle of. the propeller is substantially the. same asthat indicated by the pointer 284 but without some means for stabilizingthe operation thereof, would cause the propeller pitch to continuouslychange within. narrow limits as the arm 2.54 passed from one end of. thecontact member 240 to the adjacent end of the insulated portion of thedisc 238 and back again to the contact member. The necessary stabilizingeffect is provided by the operation of, the valve 84. An operatingcircuit for the solenoid of this valve is provided. through the conduit224, the brush 226-, the shaft 222;. the arm. I18, the contact point2I0, the conduit 21I2, the brush 2I-4, the shaft I98, the arm 252,. thecontact member 248 on the disc 246, the brush 244, and the electricalconduit 242 to one side of the solenoid and from the other side of thesolenoid through the conduit 230 back to the source. of direct current.The. arm 252. is also moved by the Autosyn through rotation. of theshaft I98 as the propeller changes pitch to make and break the circuitcontrolling the valve 84. The contact member 248 is a very narrow memberin r the direction circumferential of the disc 246,. the circumferentialextent thereof being limited by the permissible variations of thepropeller pitch from the selected pitch angle. As long as the arm252 isout of contact. with the. member. 24.8 the valve 84 remains open topermit adjustment of the propeller pitch through the operation of thevalve I84 is explained above. When the propeller pitch has been adjustedto an angle at which the arm 252 is on the contact member 248 the valve84 is immediately closed to prevent any further change in the propellerpitch. and will remain closed as long as the. arm 252 is incontact withthe member 248 thus. holding the propeller at the selected pitch angle.If because of leakage or other causes the. pitch angle diverges from theselected angle, the valve 84 will be opened upon a separation of the arm252 operation of the. valve I84. to return. the propeller to theselected pitch.

While in the. diagrammatic illustration in Fig. 1 two separate discs246. and 238 have been shown rotatable by respective gear members 210and 268 mounted on the shaft 264 which carries the selector knob 262and. a separate set of gears 208 and 266 have been shown for moving theindicating hand 204, it is to be understood that these discs and gearmembers may be combined into a compact unit utilizing a single disc andgear member.

By the above described means the desired pitch angle of the propellercan be manually selected and the mechanism will automatically bring thepropeller pitch to the selected pitch angle and maintain it atthatangle.

The Autosyn, comprising the units I86 and I95, is energized through thelines 212 and 214 from a suitable source of relatively low voltagealternating current, such as alternator, not illustrated, and thisAutosyn together with the above-described dial and indicating pointersis particularly shown in Figs. 4, 5, and 6 to which reference may now behad for a more detailed description of this element of the apparatus.

The Autosyn element I85 has a casing 2% within which is mounted anelectro-magnetic stator winding 278. Within this stator winding there isa rotatable armature 2S9 carried on a shaft 282 supported in the casing278 on suitable anti-friction bearings. Gne end of this shaft 282 isconnected with the shaft I92 through the step up gear train 285 and the:flexible connection comprising the two oppositely wound clock springs288 and 238, this arrangement being such that the shaft 92 is normallycentered relative to the shaft 282 by the springs 28% and 288' but thesetwo shafts may rotate relatively to each other in either direction ifthe resistance of the armature shaft to rotation, as for instance whenit is locked in position by the clutch 299, 292, is sufficient to windup one or the other of the springs. The opposite end of the armatureshaft is connected to a clutch plate 292 which is positioned between theend of the casing 216 and a plate 296 which is held against rotation buthas a limited freedom of movement axially of the shaft. This plate 299-is urged into engagement with the plate 292 by suitable springs, one ofwhich is indicated at 294, and is moved out of engagement with the fixedplate by an electromagnet 296 which is energized when the Autosyn isenergized. This arrangement is provided to prevent the two units I86,I96, of the Autosyn from getting out of step or the proper phaserelation with respect to each other, as might happen if the armature ofthe unit H89 were rotated at a time when the two units were notelectrically energized. With the above-described arrangement, if thecurrent is cut off the clutch plate 292 will hold the armature 2'81]fixed and any movement of the shaft 88 rotating the gear I 99 will betaken up by the springs 28% and 288 and, as the armature of the unit i96 will also remain fixed, the two units will' bemaintained in theproper phase relationshi-p with respect to each other.

Theunit I96 also includes a casing 309 within which is disposed a statorwinding 3%12 and a rotatable armature 39 mounted on an armature shaft306 supported in the casing 399' by suitable anti-friction. bearings ateach. end thereof. One end of the shaft 305 is connected direct to thepointer 292 through the pin 398' and is connected to the pointer 299through the reduction gear and the contact member 248 thus permittingthe train 3H! which preferably has. a gear ratio the same as that of thestep up gear train 284 so that movement of this pointer will be the sameas the movement of the shaft I92. The opposite end of the armature shaftcarries a ring 3I2 contacting a brush 3I4 through which energizingcurrent is supplied to the Autosyn from the alternating current source212. The two arms 252 and 254 are combined into a single arm 252a in theactual device illustrated in Figs. 5 and '1 and the contact members 240and 240 are both placed on the disc 208a which takes the place of allthree of the discs or annular members 208, 238 and 246 schematicallyshown in Fig. 1, the arrangement of the contact members being clearlyshown in Fig. 7. This is possible because the two contact arms 252 and254 are both connected with the shaft I98 and the contact members 240and 248 are angularly spaced so that they can both be placed on the samedisc without overlapping.

The construction and operation of the Autosyn has been only brieflydescribed as the general theory of such devices is well known to theprior art. Alternating current supplied to the stator windings of theunits I86 and I96 set up rotating magnetic fields which are in phasewith each other. The magnetic field thus produced in the stator windingsof one of the units induces electrical impulses in the rotor of thatunit which impulses are conducted through suitable electricalconnections to the rotor of the other unit. 7 If the rotor of the firstunit is moved relative to the stator of that unit it will produce in therotor of the second unit impulses which are out of phase with the statorfield of the second unit until the second unit rotor has moved acorresponding amount. This out of phase condition produces the necessarytorque to keep the rotor of the second unit in step with the rotor ofthe first unit.

When it is desired to feather the propeller the control knob I16 ismoved to the extreme clockwise position on the dial I14 bringing the armI 82 into contact with the point 3I6, the arm I80 into contact with thepoint 3I3 and the arm I18 into contact with the dead point 320. Thecontact between the arm I82 and the point 3I6 willenergize the solenoidof the plunger I12 moving the plunger out of the way of the limit stopI68 so that the servo-motor 86 can move the distributing valve plunger34 in a pitch increasing direction for the entire range of increasingpropeller pitch. The contact of the arm I80 with the point 3 I8 willenergize the solenoid of the solenoid valve 82 cutting oh the governorfrom the servo-motor and connecting the cylinder I08 with thepumppressure line 256 through the valve I84, the branch line 322, thevalve 82, the branch line I I4, the valve 84 and the fluid line I :6.The pressure fluid will be applied to the piston II2 as long as the pump64 continues to operate and likewise, fluid under pressure from the pump30 will be applied to the pitch changing motors I6 as long as thepropeller continues to rotate. As soon as the propeller reaches itsfeathered condition, however, its rotation will cease and the pressurein bothof the above-mentioned hydraulic systems will be discontinued. 7

If it is desired to feather the propeller while the propeller is notrotating as for example when testing the feathering action of thepropeller on the ground, the lever I16 may be moved to the featheringposition and a feathering action obtained-by closing the switch 324 toenergize the auxiliary pump driving electric motor 326. This motor,through its gear connections 328 and 330 'will rotate the pump cammember 332 which will op.- .erate the main pump 30 to supply fluid underpressure to the distributing valve 34 and through this valve to thepitch changing motor I6 and will also operate an auxiliary pump 334which will supply hydraulic fluid under pressure to the servo-motor 86from the line 256 in the manner above indicated. By a suflicientinterval of operation of the motor 326 the propeller can be brought toits feathered condition without rotation of the engine or the propeller.It is to be noted that the gear connecion including the gears 328 and330 which is actually an irreversible worm gear drive including anadditional idler gear 335, as particularly illustrated in Fig. 2, isutilized to prevent rotation of the cam member 332 when the engine andpropeller are operating and the motor 326 is de-energized. As shown inFig. 2, rotation of cam member 332 is also prevented by cam teeth 333projecting from cam member 332 beyond gear 330 and contacting pivoteddog 339. Operation of motor 326 rotating cam member 332 causes cam teeth333 to come up under dog 339 moving it to the left against the force ofspring 33'! thus operating auxiliary pump 334.

If the propeller is in a feathered condition and it is desired to returnit to the operative or constant-speed range of pitch adjustment, thepointer 204 will be moved to or left at some indicated pitch anglewithin the operative range and the selecting lever I16 will be moved toeither the manual or constant-speed control position. The switch 324will thenbe closed to energize the motor 326 and. the operation of thismotor will supply hydraulic fluid under pressure to the selector valve34 and the pitch changing motors and to the servo-motor 86 in the mannerindicated above. Since the propeller is above the itch setting of thepointer 204 the solenoid of both valves 82 and I84 will be energizedconnecting the cylinder I08 with the sump 66 so that the spring I22 maymove the servo-motor toward a lower pitch position. Assuming theposition of the servomotor has reached that corresponding to theindicated pitch angle the valve 84 will close, if the indicator knob I16is set at the manual control position, thereby preventing any furthermovement of the servo-motor or, if the knob I16 is set at theconstant-speed position, the solenoids of the valves 82, I84 and 84 willall be de-energized permitting the governor to come into operation tocontrol further movements of the servo-motor.

When it is desired to reverse the pitch of the propeller, that is tobring the propeller pitch to an angle beyond the flat pitch condition,the selector knob I16 is moved in a counter-clockwise direction to theposition at the end of the indicat ing dial I14 indicated by thedesignation REV. This will bring the arm I82 into contact with the point336, the arm I into contact with the point 338 and the arm :18 intocontact with the point 340. Contact of the arm I82 with the point 336will energize the solenoid of the electro-magnetically controlledplunger I12 to move this plunger out of the way of the limit stop I10 sothat the propeller pitch may be changed below the constant-speed rangeof pitch angle adjustment. The contact of the arm I80 with the point 338will energize the solenoid of the electro-magnetic valve 82 therebycutting oif the governor from the servo-motor 86. The contact of the armI18 with ;he point 340 will energize the solenoid of theelectro-magnetic valve I84 cutting off the pressure line 256 from theservo-motor and simultaneously connecting the line II6 with the sump 66through the valve 84, the branch line H4, the branch line 250, and theconduits 260 and I24.

This set up will permit the spring I22 to :move the shaft 88 to theleft, as viewed in Fig. .1, to its limiting left hand position thusmoving the plunger 94 of the distributor valvee lto a limiting pitchposition in which the limiting reverse pitch setting is obtained. Duringthis operation the manual control apparatus including the :knob 262 isrendered inoperative by movement of the arm I18 away from the point 2Wthrough which the current supply to the manual control apparatus passesand 'energization of the electrical mechanism is accomplished.

From the above description it will be observed that there has beendisclosed a control apparatus for a controllable-pitch propeller whichapparatus has four selectable modes of operation by means of whichpropeller pitch may be automatically controlled for constant-speedoperation, the prope'ler pitch may be manually set at any selected pi'ch angle, the propeller may be feathered or unfeathered and the ropellerpitch may be brought to a reverse pitch angle and in which the controlapparatus accurately follows up the pitch changing movements of thepropeller 'so that propeller pitch change is always stopped at the angleindicated for proper speed correction or the angle selected by theoperator which method of operation avoids an tendency of the controlapparatus to overshoot or hunt in controlling the propeller pitch. 7

While a suitable mechanical embodiment .for the purpose of disclosingthe invention'has been hereinabove described and illustrated in theaccompanying drawings, it isto be understood that the invention isnot'limited to theparticular embodiment so described and illustrated butthat such changes in the size, shape and arrangement of the variousparts may be resorted to as come within the scope of the sub-joinedclaims.

Having now described the invention so that others skilled in the art mayclearly understand the same, what it is desired to secure by LettersPatent is as follows:

1. In a propeller control providing various modes of operation fora'hydroscontrollable propeller, in combination, a propeller, a singlevalve in said propeller for controlling the application of hydraulicfluid to said propeller in all of said various operative modes, aservo-motor operatively connected with said valve, hydraulic speedresponsive means operatively connected with and controlling theoperation of said servo-motor, and manually controlled electrical means,including a plurality of electrically actuatable fluid controllingvalves, also operatively connected with said servo-motor for controllingthe operation thereof.

2. In combination with a hydro-controllable propeller, apropeller-carried hydraulic system for changing the propeller pitch,aseparate hydraulic system remote from said propeller-for controllingsaid propeller carried hydraulic system, means operatively connectingsaid two hydraulic systems, and an electrical system, including 1818C-trically actuatable fluid controlling valve means, remote from saidpropeller for controlling said hydraulic system remote from saidpropeller.

3. In combination with a hydro-controllable pitch propeller, apropeller-carried hydraulic system for changing thepropeller pitch, aseparate hydraulic system remote from said propeller :for controllingsaid propeller-carried hydraulic system, means operatively connectingsaid two 'hydraulic systems, and an electrical system including meansfor visually indicating the instant pitch 1'2 angle 01. the propellerand electrically actuatable fluid controlling valve means forcontrolling the hydraulic system remote from the propeller.

4. In a control for a controllable-pitch :propeller, pitch changing.means including a motor, means providing a constant-speed control forsaid pitch changing means including a servomotor controlled by a speedresponsive device and operatively connected with said pitch changingmeans, and manually actuatable means for disrupting the connection ofsaid speed responsive means with said servo-motor and placing saidservo-motor underimanual control, said manually actuatable meansincluding a switch and an electro-magnetic valve between said speedresponsive device and said servo-motor.

5. In a control for a feathering-type controllable-pitch propeller,pitch changing means, means providing a constant-speed controlfor saidpitch changing means within limits defined by a limit stop, andincluding a servo-motor controlled by a speed responsive device andoperatively connected with said pitch changing means, and manua'llyactuatable means for disrupting the connection of said speed responsivemeans with said servo-motor and placing said servo-motor under manualcontrol, said manually actuatable means including a switch, anelectro-magnetic valve controlled by said switch and interposed betweensaid-speed responsive device and said servo-motor, and electro-magneticmeans also controlled by said switch for retracting said limit stop inorder to provide for manually controlled feathering or reversingoperations of the propeller.

6. In a control for a controllable-pitch propeller, pitch changingmeans, means providin a constant-speed control for said pitch changingmeans including a servo-motor controlled by a speed responsive deviceand operatively connected with said pitch changing means, and manuallyactuatable means for disrupting the connection of said speed responsivemeans with said servomotor and placing said servo-motor under manualcontrol, said manually actuatable means including electrical contactmeans movable in .ac- 'cordance with changes in propeller pitch,manually settable contact meanscooperating with said movable contactmeans, and electro-magnetic means energized by engagement of saidmovable contact means with said settable contact means to discontinueoperation of said pitch changing means when the propeller pitch is at anangle corresponding to a selectedposition of said manually settablecontact means.

'7. In combination with a hydro-controllable propellenapropeller-carriedhydraulic system for changing the propeller pitch, aseparate hydraulic system remote from said propeller, including speedresponsive mechanism. and manual control means, for controlling saidpropeller-carried hydraulic system, means operatively connecting saidtwo hydraulic systems, said manual control means comprising amanually-controlled electrically actuatable valve for disabling saidspeed-responsive means and manually-controlled electrically actuatablevalve means for controlling said separate hydraulic system.

8, In a control for a controllable-pitch propeller, pitch changingmeans, means providing a constant-speed control for said pitch changingmeans including a speed responsive device, a servo-motor controlled bysaid speed responsive device and operatively connected with said pitchchanging means, a hydraulic connection between said speed responsivedevice and said servo-motor,

manually controlled electrically actuatable valve means for disablingsaid governor by blocking the connection between said speed responsivedevice and-said servo-motor, and manually controlled electricallyactuatable valve means operatively connected with said servo-motor forselectively controlling movement of said servo-motor.

9. In a control for a controllable-pitch propeller, pitch changingmeans, means providing a constant-speed control for said pitch changingmeans including a speed-responsive device, an hydraulically actuatedservo-motor controlled by said speed responsive device and operativelyconnected with said pitch changing means, and man ually actuatable meansfor disrupting the connection of said speed responsive means with saidservo-motor and placing said servo-motor under manual control, saidmanually actuatable means, including electrical contact means movable inaccordance with changes in propeller pitch, and manually settablecontact means, including contact means cooperating with said movablecontact means, electro-magnetic valve means in a connection between saidservo-motor and said speed-responsive device and in a connection betweensaid servo-motor and a source of pressure and means electricallyconnecting said electromagnetic valve means with said contact means forrendering said valve means operable to disrupt the connection betweensaid speed responsive means and said servo-motor, control the operationof said servo-motor and discontinue operation of said servo-motor whenthe propeller pitch reaches an angle corresponding to a selectedposition of said manually settable contact'means.

10. In a control for a controllable-pitch propeller, pitch changingmeans, means providing a constant speed control for said pitch changingmeans including a servo-motor operatively con-' nected with said pitchchanging means, a source of fluid pressure, a drain, a first meansoperatively connecting said source and said drain with said servo-motor,speed-responsive means, and a first valve means operatively connectedwith said speed-responsive means and located in said first connectingmeans, a second means operatively connecting said source and said drainwith said servo-motor, electrical contact means movable in accordancewith changes in propeller pitch, man ually settable contact means,comprising contact means cooperating with said movable contact means,electro-magnetic valve means controlled by said contact means, includingelectro-magnetic valve means in said first connecting means for blockingsaid first connecting means and other electro-magnetic valve means insaid second connectin means-for controllin the operation of saidservo-motor'and for hydraulically locking said servo-motor when thepropeller pitch reaches an angle corresponding toa selected position ofsaid manually settable contact means.

11. In a propeller control providing various modes of operation of ahydro-controllable propeller including constant speed operation andfeathering, in combination, a propeller, a separate hydraulic systemcarried by aid propeller including an hydraulic pitch changing motor, asource of fluid pressure; and a single control valve for controlling theflow of fluid between said source and said'motor, an hydraulic systemremote from said propeller, comprising, a servomotor operativelyconnected with said valve for operating the same, a source of fluidpressure for operating said servo-motor, and a series of individuallyoperable valves for controlling the flow of fluid to and from saidservo-motor, said series of valves comprising a speed governorcontrolled valve, andmanually controlled electrically actuatable valves,manual control means for selectively energizing said electricallyactuatable valves for disabling said speed governor controlled valve andselectively controlling said servo-motor to operate said single controlvalve and feather said propeller.v

12. In a propeller control providing various modes of operation of ahydro-controllable propeller including constant speed operation andfeathering, in combination, a propeller, a separate hydraulic systemcarried by said propeller including an hydraulic pitch changing motor, asource of fluid pressure, and a single control valve for controlling theflow of fluid between said source and said motor, an hydraulic systemremote from said propeller, comprising, a servo-motor operativelyconnected with said valve for operating the same, top means for limitingthe pitch setting of said propeller blades, a sourceof fluid pressurefor operating said servo-motor, and a series of individually operablevalves for controlling theflow of fluid to and from said servo-motor,said series of valves comprising a speed governor controlled valve, andmanually controlled electrically actuatable valves, manual control meansincluding means for disablin said sto and for selectively energizingsaid electrically actuated valves for disabling said speed governorcontrolled valve and selectively controlling said servo-motor to operatesaid single control valve and feather said propeller.

13. In a control for a hydro-controllable pitch propeller, a source offluid pressure, a drain, a motor operatively connected with saidpropeller for changing the pitch thereof, hydraulic connectionsbetweensaid motor, said source, and said drain, a speed governor, a pluralityof valves controlling the flow of fluid between said motor and saidsource and said drain, said valves comprising a control valve controlledby said speed governor and a manually controlled electrically actuatablecut off valve operable independent of the position of said control valveto render said governor ineffective to govern arranged in series in aconmotion between said moto and said source and said drain forcontrolling fluid flow between said motor and said source and saiddrain, a second electrically actuatable valve in a connection betweensaid source and said motor, and a third electrically actuatable Valve ina connection between said motor and said drain, and manually controlledmeans for selectively energizing said electrically actuatable valves tomanually control said motor.

14. In a control for a hydro-controllable pitch propeller, asource offluid pressure, a motor operatively connected with the propeller bladesfor changing the pitch thereof, an hydraulic connection between saidsource and said motor, a' speed responsive valve and an electricallyactuatable cut off valve arranged in series in said connection, asecondhydraulic connection between said source and said motor, a secondelectrically actuatable valve insaid second connection, and manuallycontrolled means for selectively energizing said electrically actuatablevalves.

'15.--In a control for a controllable-pitch propeller, pitch changingmeans including a motor,

means providing a constant-speed control for said pitch changing meansincluding a servomotor controlled by a speed-responsive device andoperatively connected with said motor, and

acszpeo manually actuatable means for disrupting the connection of saidspeed-responsive means with said servo-motor and placing saidservo-motor under manual control, said manually 'actuatable meansincluding a switch and electro-magnetic connection-disrupting meansbetween said speed-responsive device and said servo-motor.

16. In a control for a feathering-type controllable-pitch propeller,pitch changing means, means providing a constant-speed control for saidpitch changing means within limits defined by a limit stop, andincluding a servo-motor controlled by a speed-responsive device andoperatively connected with said pitch changing means, manuallyactuatable means for disrupting the connection of said speed-responsivemeans with said servo-motor and placing said servo-motor under manualcontrol, said manually actuatable means including a switch,electro-magnetic means controlled by said switch and interposed betweensaid speed responsive device and said servo-motor, and electro-magneticmeans also controlled by said switch for retracting said limit stop.

17. In the control for a feathering-type controllable-pitch propeller,pitch changing means, means providing a constant speed control for saidpitch changing means within limits defined by a limit stop, including ahydraulic servo-motor controlled by a speed-responsive device and0peratively connected with said pitch changing means, manuallyactuatable means for disrupting the connection of said speed-responsivemeans with said servo-motor and placing said servomotor under manualcontrol, said manually actuatable means including switch means,electromagnetic valve means controlled by said switch means andinterposed between said speed-responsive device and said servo-motor andelectromagnetic means also controlled by said switch means forretracting said limit stop.

18. In combination with a hydro-controllable pitch propeller, a controlunit held against rotation with said propeller and comprising, a sourceof fluid under pressure, a servo-motor, a plurality of manuallycontrolled valves and a governor including a governor valve, means forselectively actuating said manually controlled valves to selectivelyconnect said servo-motor with said source through said governor valvefor constant speed operation, or disconnect said governor from saidservo-motor and manually control the connection of said source with saidservo-motor, and a mechanical connection between said servo-motor andsaid propeller for changing the propeller pitch by movement of saidservo-motor.

19. In combination with an engine and a hydro-controllable pitchpropeller drivingly connected therewith, a separate control unit locatedbetween said engine and said propeller and held by said engine againstrotation with said propeller and comprising a source of fluid underpressure, a servo-motor, a plurality of manually controlled valves, anda governor including a governor valve, means for selectively actuatingsaid manually controlled valves to selectively connect said servo-motorwith said source through said governor valve for constant speedoperation, or disconnect said governor from said servo-motor andmanually control the connection of said source with said servo-motor,and a mechanical connection between said servo-motor and said propellerfor changing the propeller pitch by movement of said servo-motor.

20. In combination with a hydro-controllable propeller, apropeller-carried hydraulic system for changing the propeller pitch, aseparate hydraulic system remote from said propeller for controllingsaid propeller hydraulic system, means operatively connecting said twohydraulic systems, a control unit held against rotation with saidpropeller and including said separate hydraulic system, and electricallyactuatable fluid controlling valve means for controlling said remotehydraulic system.

21. In combination with an engine having a lubricating system anddrivingly connected with a hydro-controllable propeller, apropeller-carried hydraulic system for changing the propeller pitch, aseparate hydraulic system remote from said propeller for controllingsaid propeller hydraulic system, means operatively connecting said twohydraulic systems, both of said hydraulic systems being separate fromthe engine lubricating system, .a control unit held against rotationwith said propeller and including said separate hydraulic system, andelectrically actuatable fluid controlling valve means for controllingsaid remote hydraulic system.

22. In a fluid pressure actuated variable pitch propeller having pumpmeans operative upon rotational movement of the propeller for supplyingfluid under pressure, blades, a fluid motor, and mechanism connectingsaid motor with said blades for moving said blades to change their pitchand position the blades in accordance with the position of said motor, agovernor valve for automatically controlling the movement of said bladesbetween predetermined high and low pitch setting by controlling the flowof fluid between said pump and said motor, the combination (30.1.prising, means providing a source of fluid under pressure when thepropeller is not rotating, means negativing the governed control ofblade setting, and valve means having an open and a closed position andindependent of the propeller pitch, selectively manually operable uponnegativing of the governed control for applying fluid from said sourceto said motor for actuating said motor for efiecting movement of theblades to a full feathering position.

23. In a fluid pressure actuated variable pitch propeller having pumpmeans operative upon rotational movement of the propeller for supplyingfluid under pressure, blades, a fluid motor, and mechanism connectingsaid motor with said blades for moving said blades to change their pitchand position the blades in accordance with the position of said motor, agovernor valve for automatically controlling the movement of said bladesbetween predetermined high and low pitch setting by controlling the fiowof fluid between said pump and said motor, the combination comprising,means providing a source of fluid under pressure when the propeller isnot rotating, means negativing the governed control of blade setting andmanually operable valve means, operable upon negativing of the governedcontrol, for releasing fluid from said source and directing saidreleased fluid to said motor for actuating said motor for effectingmovement of the blades to a full feathering position.

24. In a control for a hydraulically-actuated controllable-pitchpropeller, pitch changing means, means providing a constant speedcontrol for said propeller including a motor controlled by a speedresponsive device and operatively connected with said pitch changingmeans, said constant speed control comprising valve means operated bychanges in propeller speeds for controlling the propeller pitch,manually actuatable means for disabling said constant speed control andmanually controlling said motor, said manually actuatable meansincluding means for manually positioning said valve means independentlyof said speed responsive device, means for supplying fluid underpressure While the propeller is not rotating and manually controlledvalve means for controlling the application of fluid from said fluidsupply to said motor.

25. In a control for a hydraulically actuated controllable pitchpropeller, a governor including a governor valve, a source of hydraulicfluid under pressure energized incident to rotation of said propeller,pitch changing mechanism, a motor operatively connected with saidpropeller pitch changing mechanism, said governor valve being connectedby fluid conduits with said source and said motor to change propellerpitch in response to changes in speed, a second source of fluid underpressure available when the propeller is not rotating, a manual controlfor said propeller, said manual control including means disablingcontrol by said governor, and means, including manually actuatable valvemeans, selectively making said second source of fluid available forpitch changing operation and directing fluid from said second source tosaid motor.

26. In a control for a hydraulically actuated controllable pitchpropeller, a governor including a governor valve, a source of hydraulicfluid under pressure energized incident to rotation of said propeller,pitch changing mechanism, a motor operatively connected with saidpropeller pitch changing mechanism, said governor valve being connectedby fluid conduits with said source and said motor to change propellerpitch in response to changes in speed, a second source of fluid underpressure available when the propeller is not rotating, a manual controlfor said propeller, said manual control including means disablingcontrol by said governor, a manually actuatable valve between saidsecond source and said motor, manually actuated means for operating saidmanually actuatable valve including means for opening said manuallyactuatable valve, and means directing fluid from saidsecond sourcethrough said open manually actuatable valve to said motor to feather thepropeller.

27. In a control for a hydraulically actuated controllable pitchpropeller, a governor including a governor valve, 2. source of hydraulicfluid under pressure energized incident to rotation of said propeller,pitch changing mechanism, a motor operatively connected with saidpropeller pitch changing mechanism, said governor valve being connectedby fluid conduits with said source and said motor to change propellerpitch in response to changes in speed, a second source of fluid underpressure available when the propeller is not rotating, a manual controlfor said propeller, said manual control including means disablingcontrol by said governor, a manually actuatable valve between saidsecond source and said motor, manually actuated means for operating saidvalve including means for opening said valve, means directing fluid fromsaid second source through said open valve to said motor to feather thepropeller, means operatively connecting said disabling means and saidmanually actuated valve operating means, and a single manuallycontrolled actuating means for both said disabling means and said valveoperating means.

NELSON R. RICHMOND. MAURICE J. LEVY, Administrator of estate of DonaldW. Perz'n,

deceased.

References Cited in the file of this patent UNITED, STATES PATENTSNumber Name Date Re. 22,034 Hoover Feb. 24, 1942 719,283 Weber Jan. 27,1903 1,106,434 Woodward Aug. 11, 1914 1,147,820 Scott July 27, 19151,291,566 Lewis Jan. 14, 1919 1,375,269 Akemann Apr. 19, 1921 1,465,723West Aug. 21, 1923 1,695,159 Burch June 26, 1928 1,990,814 Castro Feb.12, 1935 2,017,086 Zouck Oct. 15, 1935 2,023,785 Hoover Dec. 10, 19352,030,986 Havill Feb. 18, 1936 2,128,983 Blanchard Sept. 6, 19382,145,850 Caldwell Feb. 7, 1939 2,146,401 Manchester Feb. 7, 19392,163,663 Caldwell June 27, 1939 2,192,790 Havill Mar. 5, 1940 2,221,365Ware Nov. 12, 1940 2,229,058 Dicks Jan. 21, 1941 2,232,838 Bryant Feb.25, 1941 2,243,095 Hammond May 27, 1941 2,279,301 Colley et al Apr. 14,1942 2,280,713 Martin et al Apr. 21, 1942 2,307,102 Blanchard et a1 Jan.5, 1943 FOREIGN PATENTS Number Country Date 299,254 Italy July 26, 1932476,852 Great Britain Dec. 16, 1937 499,634 Great Britain Jan. 26, 1939517,696 Great Britain Feb. 6, 1940

